I used to worry about that with my 70 vert Cuda', which is a total rust bucket money pit of a POS, but it's mine...
SO, I'm cloning a 71 since nothing will be "original" anyway and I prefer the 71 over the 70. Technically, the things I'll be changing can be reversed with a pile of front end sheetmetal, some tail lights and a few other detail things followed by a paint job. Won't ever be my problem.